Claritas

I've read the details, I just can't imagine where to use <a rel="tag"> and <a rel="next"> in practice at a website.

http://www.w3schools.com/tags/att_a_rel.asp What does it mean to be selection between documents? (Next, Prev) How can we imagine a tag link? (Tag)

What does it mean to be two dimensional? May you give me an example for it?

I was reading the reference (http://www.w3schools.com/tags/att_a_media.asp) and I've got a few question. - What is the difference between width and device-width and when are we using them? - What is the difference between aspect-ratio and device-aspect-ratio and when are we using them? - What is the difference between bits per color and number of colors and when are we using them? - What is a monochrome frame buffer, scanning method and grid or bitmap? Thanks for the anwers.